The venoms of six representative species of rattlesnake of the family Crotalidae will be characterized for their biologically active peptides and non-enzymatic proteins, using such techniques as gel filtration, ion exchange chromatography, gel electrophoresis, dialysis, ultrafiltration, ultracentrifugation and ammonium sulfate precipitation. Further chemical characterization, including amino acid analysis, and amino acid sequence will be carried out. The physio-pharmacological properties of the individual fractions of the venoms will be determined, using cardiovascular survey preparations, the rabbit ear artery-nerve preparation, isolated heart and vascular tissue preparations, the Bulbring nerve-muscle preparation, the crayfish DEAM preparation and techniques adapted for determining the hemorrhagic and necrotizing properties of venoms. Among other applications, the data will be organized for the potential use of developing an immunizing mixture of certain of the venom components for subsequent research and clinical trial. The value of the peptides in medicine and as biological tools will be considered. The data will also be studied for its taxonomic significance. BIBLIOGRAPHIC REFERENCES: Effects of the venom of the rattlesnake, Crotalus viridis helleri on vascular smooth muscle. Pattabhiraman, T. R., Whigham, H., Lui, A. H. F. and Russell, F. E. Presented at Western Pharmacology Society Meeting, San Francisco, January, 1976. (in press). Hemodynamic response in the dog to rattlesnake venom Crotalus viridis helleri: special reference to effects on systemic venous return. Whigham, H., Lui, A.H.F., Pattabhiraman, T. R. and Russell, F.E. Presented at Western Pharmacology Society Meeting, San Francisco, January, 1976. (in press).